Safari 4 faster, more stable on Snow Leopard than 10.5.x

Though many readers have reported the problems with Safari 4.x on Leopard, few of the same issues were reproducible by testers/developers and sources who have hands-on access to the latest post-WWDC builds (10a380 and later) of Snow Leopard.

We’ve noted the considerable boost to Safari 4 performance that users of Mac OS X 10.6 build 10a380 have experienced in previous posts to our Twitter feed, and it would appear that a similar difference applies to many of the stability problems readers have been reporting with 10.5.x, even after the recent Safari 4.0.1 Update is applied.

In fact, in several cases, it would appear that v4.0.1 actually made some of these issues worse. Paradoxically, though the 4.0.1 Update package is not available for Snow Leopard (requires 10.5.7) and 10.6 is still almost three months away from release with plenty of system-level bugs left to be fixed, virtually all testers we talked to were left scratching their heads in surprise when attempts were made to reproduce the widely reported crashes/misbehavior on 10a380 or more recent builds.

Although virtually everything is faster on Snow Leopard — even on previous-generation Intel Macs which don’t support SL’s more advanced features such as 64-bit processing & OpenCL GPU acceleration — the difference between 10.5 & 10.6 when comparing popular Web browsers such as Firefox and Opera is not nearly so dramatic. In fact, both browsers (3.5rc3 and 9.6, respectively) are actually slightly less stable on 10.6 10a380 as compared with 10.5.7 or even the most recent 10.5.8 builds.

The difference would seem to be accounted for by statements from Apple sources close to Snow Leopard and high-level Safari development confirming the long-held belief on the grapevine that Safari 4 has been primarily developed with Snow Leopard as its intended target, rather than 10.5.x. Though most things across the two operating systems are consistent in terms of APIs, so much has been changed at the low level and for important application-system interface functions such as threading (Snow Leopard’s “Grand Central Dispatch,” which is a large part of its performance/multitasking gains) that bugs cropping up for users of 10.5.x — particularly those on PowerPC Macs — are nearly inevitable.

The strange part is that these bugs seem to have taken some time to gain widespread attention, and that there seem to be problems at Infinite Loop in terms of rapidly addressing them. There was hope that the 4.0.1 Update, being targeted exclusively at Mac OS X 10.5.7, would fix the issues noted immediately after 4.0’s initial release on June 8th….but ironically, for many users this seemed to only make matters worse.

Stay tuned to Rumors for further updates on this, as we dig deeper into what is really behind all this — and for in-depth reviews of recent builds of both Mac OS X 10.5.8 “Athena” and 10.6 “Snow Leopard.”